It is well known that ultraviolet rays have a bad influence upon photographic light-sensitive materials. In the photographic light-sensitive materials, a light-sensitive photographic emulsions containing silver halide as a chief component is generally applied to a support having a relatively high electrical insulating property such as a film composed of triacetyl cellulose, polyethylene terephthalate, polystyrene or polycarbonate, or a laminated paper covered therewith, and the surface of the photographic light-sensitive materials has a fairly high electrical insulating property. Therefore, when the surface of the photographic light-sensitive material comes in contact with the same or different kind of material during production or treatment of the photographic light-sensitive material, electric charges are generated by friction or separation. This phenomenon is called charging. When accumulation of static electricity by charging reaches a certain limiting value, atmospheric discharge occurs at a particular moment and a discharge spark flys at the same time. When the photographic light-sensitive material is exposed to light by discharging, branched, feathered, spotted or radial images appear after development. Images formed by such a phenomenon are called static marks in the photographic field. It has been known that a distribution of spectral energy of this kind of discharge luminescence which causes static marks is in a range of 200 nm to 550 nm and, particularly, the intensity thereof is high in a range of 300 nm to 400 nm, and light energy in this range causes occurrence of static marks. Accordingly, attempts have been made to prevent the occurrence of static marks by shielding ultraviolet rays in a range of 300 to 400 nm by means of ultraviolet ray absorbing agents, as described in, for example, Japanese Patent Publication No. 10726/75 (corresponding to British Pat. No. 1,378,000 and German Pat. No. 2,163,904), Japanese Patent Application (OPI) No. 26021/76 (corresponding to Belgian Pat. No. 832,793) (the term "OPI" as used herein refers to a "published unexamined Japanese patent application") and French Pat. No. 2,036,679 (corresponding to Belgian Pat. No. 755,781), etc.
Further, excepting light-sensitive materials such as light-sensitive materials for printing which are exposed to a specific light source or light-sensitive materials for X-rays, etc., the conventional photographic light-sensitive materials are sometimes subject to an undesirable influence by ultraviolet rays included in light to be used for exposure. For example, in black-and-white light-sensitive materials, objects to be photographed which have a remarkably large quantity of spectral energy in an ultraviolet region, such as a snow scene, a seashore or the sky, etc., easily form soft tone images. In color light-sensitive materials, since it is desired to record only visible light, the influence of ultraviolet rays is very apparent. For example, when photographing the object which have a comparatively large quantity of spectral energy in the ultraviolet region, such as a distant view, a snow scene or an asphalted road, etc., the resulting color images are rich in cyan color. Further, color reproduction in color images is notably different according to light sources to be used for exposure, such as the sun, a tungsten lamp or a fluorescent lamp, etc. The cause of the difference is a difference of spectral energy in the ultraviolet region of light from these light sources. Namely, color images obtained by being exposed to light emitted from a tungsten lamp become more reddish and those obtained by being exposed to light emitted from a fluorescent lamp become more bluish than those obtained by being exposed to sunlight. Accordingly, in order to obtain color photographic images which have correct color reproduction, it is desirable to prevent ultraviolet rays from reaching the silver halide light-sensitive layer of the color light-sensitive material when photographing. Examples of attempts at such have been described in, for example, Japanese Patent Application (OPI) Nos. 56620/76 (corresponding to U.S. Pat. No. 4,045,229) and 49029/77 (corresponding to U.S. Pat. No. 4,200,464).
Furthermore, color photographs and, particularly, dye images formed on the light-sensitive emulsion layers by color development easily fade or discolor due to the action of ultraviolet rays. Color formers remaining in the emulsion layers after formation of color images are subject to the action of ultraviolet rays to form undesirable color stains on the finished photographs. This kind of action of ultraviolet rays on color photographs finished by photographic treatment is particularly remarkable with positive prints observed under sunlight containing a large quantity of ultraviolet rays. The fading and the discoloration of color images are easily caused by ultraviolet rays having wavelengths near the visible region, namely, those having spectral energy in the area of 300 nm to 400 nm. Examples of useful ultraviolet ray absorbing agents which act in reducing bad influences caused by these types of ultraviolet rays are described in U.S. Pat. Nos. 3,215,530, 3,707,375, 3,705,805, 3,352,681, 3,278,448, 3,253,921 and 3,738,837, Japanese Patent Publication Nos. 26138/74 and 25337/75, British Pat. No. 1,338,265 and Japanese Patent Application (OPI) No. 56620/76 (corresponding to U.S. Pat. No. 4,045,229), etc.
Hitherto, a number of ultraviolet ray absorbing agents have been proposed for one or more purposes as described above. However, ultraviolet ray absorbing agents used hitherto for silver halide photographic light-sensitive materials are not sufficiently suitable for the above described uses, because they color and form stains due to their insufficient stability to ultraviolet rays, heat and humidity. Further, they have inferior compatibility with binders, they diffuse into other layers caused bad influences due to substantial interlayer migration, or the emulsion thereof may be unstable causing deposition of crystals. Further, these ultraviolet ray absorbing agents have been frequently used in a surface protective layer of silver halide photographic light-sensitive materials, and when a high boiling point organic solvent is used for emulsification of the ultraviolet ray absorbing agents, the high boiling point organic solvent makes the layer soft and substantially deteriorate interlayer adhesion or anti-adhesive property. In order to prevent such problems, it is necessary to use a large amount of gelatin or to provide a gelatin protective layer on the layer. This results in thickening the layer containing the ultraviolet ray absorbing agent even though it is desirable to reduce the thickness of the layer.
An example of a type of ultraviolet ray absorbing agent which does not have such disadvantages is a polymer ultraviolet ray absorbing agent. However, such agents are insufficient for solving these problems.
As a result of extensive investigations, it has been found that these problems can be completely solved by using a polymer latex obtained by polymerization of certain kinds of ultraviolet ray absorbing monomers.
Two processes for adding polymer ultraviolet ray absorbing agents in the form of latex to a hydrophilic colloid composition are known. One process comprises adding a latex prepared by emulsion polymerization directly to a hydrophilic colloid. Another process comprises dispersing a hydrophobic polymer ultraviolet ray absorbing agent obtained by polymerization of ultraviolet ray absorbing monomers in an aqueous solution of gelatin in the form of latex. Such ultraviolet ray absorbing polymer latexes have been described in, for example, U.S. Pat. Nos. 3,761,272 and 3,745,010, Japanese Patent Application (OPI) No. 107835/78 and European Pat. No. 27242, etc.
The processes for adding the polymer ultraviolet ray absorbing agents in the form of latex to a hydrophilic colloid composition have many advantages as compared with other processes.
First, (1) it is not necessary to use a high boiling point organic solvent used hitherto, because a hydrophobic material is in the form of a latex, (2) strength of the film formed from the latex is not deteriorated, (3) it is possible to easily incorporate the ultraviolet ray absorbing agent in a high concentration in the hydrophilic colloid layer, because the latex can contain ultraviolet ray absorbing monomers in a high concentration, and (4) an increase of viscosity is small. Further, (5) other layers are not affected since they are completely immobilized, and (6) deposition of the ultraviolet ray absorbing agents in the hydrophilic colloid layer is small and the thickness of the hydrophilic colloid layer can be reduced. Particularly, when the ultraviolet ray absorbing polymer latex is produced by emulsion polymerization a specific method for dispersing is not required and the step of adding the ultraviolet ray absorbing agent to the coating solution can be simplified. However, though the ultraviolet ray absorbing polymer latexes known hitherto have several excellent advantages as described above, they have the following problems.
1. Since the absorption peak of the ultraviolet ray absorbing agent becomes broad, stains are formed or sensitivity of the silver halide emulsion is unnecessary reduced.
2. The absorption characteristic in a range of 300 nm to 400 nm is poor, and the effect of preventing static marks and color reproduction is inferior.
3. Since the ultraviolet ray absorbing agent itself is not sufficiently stable to ultraviolet rays, heat and humidity, it colors and causes stains.
4. Ultraviolet ray absorbing monomers have low solubility and poor polymerization ability.
5. It is necessary to add a large amount of the latex in order to obtain a desired density, because the ultraviolet ray absorbing monomers have a low absorption coefficient.
The broadening in the absorption peak of the ultraviolet ray absorbing agent having the absorption maximum in a range of about 360 nm to about 400 nm has a great influence upon the photographic properties. Such ultraviolet ray absorbing polymer latexes which absorb ultraviolet rays in the range of about 360 nm to about 400 nm are described in European Pat. No. 27242. However, these polymer latexes are still not sufficient since they have several disadvantages in that they have a bad influence upon the photographic properties, for example, the formation of stains or the decrease in the sensitivity of the silver halide emulsion due to the broadening in the absorption peak thereof, and in that the polymerization ability of the ultraviolet ray absorbing monomers used is very poor, etc.